Liquid crystal display device

ABSTRACT

A liquid crystal display device includes a first substrate and a second substrate. The first substrate includes a gate line and an auxiliary capacitance line extending in a first direction, a source line extending in a second direction orthogonally crossing the first direction, and a pixel electrode having a main pixel electrode arranged on the auxiliary capacitance line and extending in the first direction. The second substrate includes a common electrode having a main common electrode arranged above the gate line and extending in the first direction. A liquid crystal layer is held between the first substrate and the second substrate having liquid crystal molecules. The liquid crystal molecules are initially aligned in the first direction in a splay alignment state between the first substrate and the second substrate in a state where electric field is not formed between the pixel electrode and the common electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 14/323,643filed Jul. 3, 2014, which is a divisional of U.S. application Ser. No.14/186,843 filed Feb. 21, 2014, which is a divisional of U.S.application Ser. No. 13/549,013 filed Jul. 13, 2012, and is based uponand claims the benefit of priority from prior Japanese PatentApplication No. 2011-203773, filed Sep. 16, 2011, the entire contents ofeach of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

In recent years, a flat panel display is developed briskly. Especially,the liquid crystal display device gets a lot of attention fromadvantages, such as light weight, thin shape, and low power consumption.In an active matrix type liquid crystal display device equipped with aswitching element in each pixel, a structure using lateral electricfield, such as IPS (In-Plane Switching) mode and FFS (Fringe FieldSwitching) mode, attracts attention. The liquid crystal display deviceusing the lateral electric field mode is equipped with pixel electrodesand a common electrode formed in an array substrate, respectively.Liquid crystal molecules are switched by the lateral electric fieldsubstantially in parallel with the principal surface of the arraysubstrate.

On the other hand, another technique is also proposed, in which theliquid crystal molecules are switched using the lateral electric fieldor an oblique electric field between the pixel electrode formed in thearray substrate and the common electrode formed in a counter substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute aportion of the specification, illustrate embodiments of the invention,and together with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a figure schematically showing a structure and the equivalentcircuit of a liquid crystal display device according to an embodiment.

FIG. 2 is a plan view schematically showing a structure when an arraysubstrate shown in FIG. 1 is seen from a counter substrate sideaccording to the embodiment.

FIG. 3A is a plan view schematically showing the structure of one pixelin the counter substrate shown in FIG. 1.

FIGS. 3B and 3C show the relationship between a polarization axis and aninitial alignment direction.

FIG. 4 is a cross-sectional view schematically showing the structure ofthe liquid crystal display panel taken along line A-B shown in FIG. 3A,seen from a source line S1 side.

FIG. 5 is a cross-sectional view schematically showing the structure ofthe liquid crystal display panel taken along line C-D shown in FIG. 3A,seen from a gate line G2 side.

FIG. 6 is a figure schematically showing an alignment state of liquidcrystal molecules in a liquid crystal layer at the time of OFF.

FIG. 7 is a figure schematically showing the alignment state of theliquid crystal molecules in the liquid crystal layer at the time of ON.

FIGS. 8A, 8B and 8C are figures showing variations of the pixelstructures according to the embodiment.

FIGS. 9A and 9B are figures showing variations of the pixel structuresaccording to the embodiment.

FIGS. 10A, 10B, 10C and 10 D are figures showing variations of the pixelstructures according to the embodiment.

DETAILED DESCRIPTION

A liquid crystal display device according to an exemplary embodiment ofthe present invention will now be described with reference to theaccompanying drawings wherein the same or like reference numeralsdesignate the same or corresponding portions throughout the severalviews.

According to one embodiment, a liquid crystal display device includes: afirst substrate including; a gate line and an auxiliary capacitance lineextending in a first direction, a source line extending in a seconddirection orthogonally crossing the first direction, a switching elementelectrically connected with the gate line and the source line, a pixelelectrode having a main pixel electrode arranged on the auxiliarycapacitance line and extending in the first direction, the pixelelectrode being connected with the switching element, and a firstalignment film covering the pixel electrode, a second substrateincluding; a common electrode having a main common electrode arrangedabove the gate line and extending in the first direction, and a secondalignment film covering the common electrode, a liquid crystal layerheld between the first substrate and the second substrate having liquidcrystal molecule, the liquid crystal molecule being initially aligned inthe first direction and being aligned in a splay alignment state betweenthe first substrate and the second substrate in a state where electricfield is not formed between the pixel electrode and the commonelectrode.

FIG. 1 is a figure schematically showing the structure and theequivalent circuit of a liquid crystal display device according to theembodiment.

The liquid crystal display device includes an active-matrix type liquidcrystal display panel LPN. The liquid crystal display panel LPN isequipped with an array substrate AR as a first substrate, a countersubstrates CT as a second substrate arranged opposing the arraysubstrate AR, and a liquid crystal layer held between the arraysubstrate AR and the counter substrate CT. The liquid crystal displaypanel LPN includes an active area ACT which displays images. The activearea ACT is constituted by a plurality of pixels PX arranged in theshape of a (m×n) matrix (here, “m” and “n” are positive integers).

The liquid crystal display panel LPN is equipped with “n” gate lines G(G1-Gn), “n” auxiliary capacitance lines C (C1-Cn), “m” source lines S(S1-Sm), etc., in the active area ACT. The gate line G and the auxiliarycapacitance line C correspond to signal lines extending in a firstdirection, respectively. The gate line G and the auxiliary capacitanceline C are arranged in turns along a second direction Y thatorthogonally intersects the first direction X. The source lines S crossthe gate line G and the capacitance line C. The source lines S extendlinearly in the second direction Y, respectively. The gate line G, theauxiliary capacitance line C and the source lines S do not necessarilyextend linearly, and a portion thereof may be crooked partially.

Each gate line G is pulled out to outside of the active area ACT, and isconnected to a gate driver GD. Each source line S is pulled out to theoutside of the active area ACT, and is connected to a source driver SD.At least a portion of the gate driver GD and the source driver SD isformed in the array substrate AR, for example. The gate driver GD andthe source driver SD are connected with the driver IC chip 2 provided inthe array substrate AR and having an implemented controller.

Each pixel PX includes a switching element SW, a pixel electrode PE, acommon electrode CE, etc. Retention capacitance Cs is formed, forexample, between the auxiliary capacitance line C and the pixelelectrode PE. The auxiliary capacitance line C is electrically connectedwith a voltage impressing portion VCS to which the auxiliary capacitancevoltage is impressed.

In addition, in the liquid crystal display panel LPN according to thisembodiment, while the pixel electrode PE is formed in the arraysubstrate AR, at least one portion of the common electrode CE is formedin the counter substrate CT. Liquid crystal molecules of the liquidcrystal layer LQ are switched mainly using an electric field formedbetween the pixel electrode PE and the common electrode CE. The electricfield formed between the pixel electrode PE and the common electrode CEis a lateral electric field substantially in parallel with the principalsurface of the array substrate AR or the principal surface of thecounter substrate CT, or an oblique electric field slightly oblique withrespect to the principle surfaces of the substrate.

The switching element SW is constituted by an n channel type thin filmtransistor (TFT), for example. The switching element SW is electricallyconnected with the gate line G and the source line S. The (m×n)switching elements SW are formed in an active area ACT. The switchingelement SW may be either a top-gate type or a bottom-gate type. Thoughthe semiconductor layer is formed of poly-silicon, the semiconductorlayer may be formed of amorphous silicon.

The pixel electrode PE is arranged in each pixel and electricallyconnected with the switching element SW. The common electrode CE isarranged in common to the pixel electrodes PE of a plurality of pixelsthrough the liquid crystal layer LQ. Though the pixel electrode PE andthe common electrode CE are formed by light transmissive conductivematerials, such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO),etc., other metals such as aluminum may be used.

The array substrate AR includes an electric power supply portion VSformed outside of the active area ACT to impress a voltage to the commonelectrode CE. Furthermore, the common electrode CE is drawn to outsideof the active area ACT and electrically connected with an electric powersupply portion VS formed in the array substrate AR through an electricconductive component which is not illustrated.

FIG. 2 is a plan view schematically showing the structure of one pixelwhen the array substrate AR according to the embodiment is seen from thecounter substrate side. Herein, a plan view in a X-Y plane is shown.

The array substrate AR is equipped a gate line G1, a gate line G2, anauxiliary capacitance line C1, a source line S1, a source line S2, aswitching element SW, a pixel electrode PE, and a first alignment filmAL1, etc. In the illustrated example, the array substrate AR is furtherequipped with a gate shield electrode GS.

In FIG. 2, the pixel PX has the shape of a rectangle whose length in thefirst direction X is shorter than the length in the second direction Y,as shown in a dashed line. The pixel includes a pair of short endslocated on the gate line G1 and the gate line G2 and a pair of long endslocated on the source line S1 and the source line S2. The gate line G1and the line G2 are arranged along the second direction Y with a firstpitch and extend along the first direction X, respectively. Theauxiliary capacitance line is arranged between the gate line G1 and thegate line G2 and extends in the first direction X. The source line S1and the source line S2 are arranged with a second pitch in the firstdirection X and extend along the second direction Y, respectively.

In the illustrated example, the source line S1 is arranged at theleft-hand side end in the pixel PX. Precisely, the source line S1 isarranged striding over a boundary between the illustrated pixel and apixel PX adjoining the illustrated pixel PX on the left-hand side. Thesource line S2 is arranged at the right-hand side end. Precisely, thesource line S2 is arranged striding over a boundary between theillustrated pixel and a pixel PX adjoining the illustrated pixel PX onthe right-hand side. The length of the pixel along the first direction Xcorresponds to the second pitch between the source lines.

Moreover, in the pixel PX, the gate line G1 is arranged at an upper endportion. Precisely, the gate line G1 is arranged striding over aboundary between the illustrated pixel and a pixel which adjoins theillustrated pixel PX on its upper end side. The gate line G2 is arrangedat a lower end portion. Precisely, the gate line G2 is arranged stridingover a boundary between the illustrated pixel and a pixel adjoining theillustrated pixel PX on its lower end side. That is, the length alongthe second direction Y corresponds to the first pitch between the gatelines. The first pitch is larger than the second pitch.

Moreover, in the illustrated pixel PX, the auxiliary capacitance line C1is arranged in the center of the pixel, i.e., substantially in thecenter between the gate line G1 and the gate line G2. The distancebetween the auxiliary capacitance line C1 and the gate line G1 in thesecond direction Y is same as that that between the auxiliarycapacitance line C1 and the gate line G2 in the second direction Y.

The switching element SW is electrically connected with the gate line G2and the source line S1 in the illustrated example. Namely, the switchingelement SW is formed in an intersection of the gate line G2 with thesource line S1. A gate electrode of the switching transistor SW isconnected with the gate line G2, and a source electrode WS is connectedwith the source line S1. A drain electrode connected with a drain lineextending along the source line S1 and the auxiliary capacitance line C1is electrically connected with the pixel electrode PE in a region whichoverlaps with the auxiliary capacitance line C1. The switching elementSW is formed in the overlapped region with the source line S1 and theauxiliary capacitance line C1, and hardly runs off the overlappedregion. Thereby, reduction of the area of an aperture portion whichcontributes to a display is suppressed when the switching element SW isarranged in the pixel PX.

The pixel electrode PE is located between the gate line G1 and the gateline G2 while it is located between the adjoining source line S1 and thesource line S2. That is, the pixel electrode PE is located in the innerside surrounded by the source line S1 and the source line S2, and thegate line G1 and the gate line G2.

The pixel electrode PE is equipped with a main pixel electrode PAlocated on the auxiliary capacitance line C1. The main pixel electrodePA is located between a first intersection portion CR1 in which thesource line S1 and the auxiliary capacitance line C1 intersect and asecond intersection portion CR2 in which the source line S2 and theauxiliary capacitance line C1 intersect, and linearly extends betweenthe first intersection portion CR1 and the second intersection part CR2along the first direction X. The main pixel electrode PA is formed inthe shape of a belt with the substantially same width along the seconddirection Y. The length of the pixel electrode PA in the first directionis shorter than the second pitch between the source lines.

The pixel electrode PE is arranged between the gate line G1 and the gateline G2. The gate line G1 and the gate line G2 are located on the bothsides which sandwich the pixel electrode PE. In the illustrated example,the pixel electrode PE is arranged substantially in a center portionbetween the gate line G1 and the gate line G2, i.e., the center of thepixel PX. For this reason, the distance between the gate line G1 and themain pixel electrode PA in the first direction Y is substantially thesame as that between the gate line G2 and the main pixel electrode PA inthe second direction Y.

The gate shield electrodes GS counter with the gate line G in the X-Yplane, respectively, and linearly extend along the first direction X inparallel with an extending direction of the first pixel electrode PA.The gate shield electrode GS is formed in the shape of a belt withsubstantially the same width along the second direction Y.

In the illustrated example, the pair of the gate shield electrodes GS isarranged in parallel with a predetermined distance therebetween in thesecond direction Y, and arranged in the upper-and-lower both ends of thepixel PX, respectively. Hereinafter, in order to distinguish the pair ofthe gate shield electrodes GS, the gate shield electrode on the upperside in the figure is called GS1, and the gate shield electrode GS onthe lower side in the figure is called GS2. The gate shield electrodeGS1 counters with the gate line G1. The gate shield electrode GS2counters with the gate line G2.

In the pixel PX, the gate shield electrode GS1 is arranged at the upperend portion, and the gate shield electrode GS2 is arranged at the lowerend portion. Precisely, the gate shield electrode GS1 is arrangedstriding over a boundary between the illustrated pixel and an adjoiningpixel PX on its upper side, and the gate shield electrode GS2 isarranged striding over a boundary between the illustrated pixel and anadjoining pixel PX on its lower side. That is, in the example shownhere, the gate shield electrode GS arranged on the array substrate AR isformed in the shape of a stripe, and is electrically connected with theelectric power supply portion VS, and becomes the same potential as thecommon electrode CE. For this reason, the gate shield electrode GS has acombined function with the common electrode CE which can form electricfield with the pixel electrodes PE.

The following relations can be said if its attention is paid to thespatial relationship between the pixel electrode PE and the gate shieldelectrode GS.

In the X-Y plane, the pixel electrode PA and the gate shield electrodeGS are arranged by turns along the second direction Y. The pixelelectrode PA and the gate shield electrode GS are arranged substantiallyin parallel each other. At this time, none of the gate shield electrodesGS overlaps with the pixel electrode PE in the X-Y plane. One pixelelectrode PE is located between the adjoining gate shield electrode GS1and gate shield electrode GS2. That is, the gate shield electrode GS1and the gate shield electrode GS2 are arranged on the both sides whichsandwich the pixel electrode PA. For this reason, the gate shieldelectrode GS1, the first main pixel electrode PA, and the gate shieldelectrode GS2 are arranged along the second direction Y in this order.

The inter-electrode distance between the main pixel electrode PA and thegate shield electrode GS is substantially the same in the seconddirection Y. That is, the inter-electrode distance between the mainpixel electrode PA and the gate shield electrode GS1 is substantiallythe same as that between the gate shield electrode GS2 and the mainpixel electrode PA in the second direction Y.

In the array substrate AR, the pixel electrode PE and the gate shieldelectrode GS are covered with a first alignment film AL1. Alignmenttreatment (for example, rubbing processing or optical alignmentprocessing) is made to the first alignment film AL1 along a firstalignment direction PD1 to initially align the liquid crystal moleculeof the liquid crystal layer LQ. The first alignment treatment directionPD1 is substantially in parallel with the first direction X in which thepixel electrode PA extends.

FIG. 3A is a plan view schematically showing the structure of the PX inthe counter substrate CT shown in FIG. 1. Herein, the plan view in theX-Y plane is shown. In addition, only structures required forexplanation are illustrated. The dashed line shows principal portions ofthe array substrate, such as the pixel electrode PE, the gate shieldelectrode GS, the source line S, the gate line G, and the auxiliarycapacitance line C, etc.

The counter substrate CT is equipped with the main common electrode CA.For example, on the outside of active area, the main common electrode CAis electrically connected with electric supply portion VS and the gateshield electrode GS formed on the array substrate, and set to the samepotential as the gate shield electrode GS.

The main common electrode CA linearly extends on both sides sandwichingthe pixel electrode PA in parallel with the first direction X in whichthe pixel electrode PA extends in the X-Y plane. The main commonelectrode CA faces the gate shield electrode GS and extends along thefirst direction X in parallel with the direction in which the pixelelectrode PA extends. While the main common electrodes CA are locatedabove the gate line G, the main common electrodes CA are located on thepair of short ends of the pixel, respectively. The main commonelectrodes CA are formed with the substantially same width along thesecond direction Y

In the illustrated example, the pair of main common electrodes CA isarranged in the first direction X in parallel, with a predetermineddistance therebetween. That is, two main common electrodes CA in onepixel are arranged along the second direction Y with the same pitch. Inthe pixel, the main common electrode CA1 is arranged on the upper endportion, and the main common electrode CA2 is arranged on the lower endportion. Precisely, the main common electrode CA1 is arranged stridingover a boundary between the illustrated pixel and an adjoining pixel onits upper-hand side. The main common electrode CA2 is arranged stridingover a boundary between the illustrated pixel and an adjoining pixel onits lower-hand side. The main common electrode CA1 faces the gate shieldelectrode GS1, and is located above the gate line G1. The main commonelectrode CA2 faces the gate shield electrode GS2, and is located abovethe gate line G2.

The main common electrode CA1 and the main common electrode CA2 arelocated in the both sides which sandwich the main pixel electrode PA inthe X-Y plane. That is, in the X-Y plane, the main common electrode CAand the main pixel electrode PA are located by turns along the seconddirection Y. In the illustrated example, the main common electrode CA1,the main pixel electrode PA, and the main common electrode CA2 arelocated with this order. In addition, the inter-electrode distancebetween the main pixel electrode PA and main common electrode CA1 in thesecond direction Y is substantially the same as that between the maincommon electrode CA2 and the main pixel electrode PA.

The common electrode CE is covered with a second alignment film AL2 inthe counter substrate CT. Alignment treatment (for example, rubbingprocessing or optical alignment processing) is made to the secondalignment film AL2 along a second alignment treatment direction PD2 toinitially align the liquid crystal molecule of the liquid crystal layerLQ. The second alignment treatment direction PD2 is in parallel with andthe same direction as the first alignment treatment direction PD1.

FIG. 4 is a cross-sectional view schematically showing a structure takenalong line A-B in the liquid crystal display panel LPN shown in FIG. 3A,seen from the source line S1 side. FIG. 5 is a cross-sectional viewschematically showing a structure taken along line C-D in the liquidcrystal display panel LPN in FIG. 3A, seen from the gate line G2 side.In addition, only the required portions for explanation are illustratedhere.

A backlight 4 is arranged on the back side of the array substrate AR inthe illustrated example. Various types of backlights 4 can be used. Forexample, a light emitting diode (LED) or a cold cathode fluorescent lamp(CCFL), etc., can be applied as a light source of the backlight 4, andthe explanation about its detailed structure is omitted.

The array substrate AR is formed using a first transmissive insulatingsubstrate 10. The array substrate AR includes the gate line G1, the gateline G2, the auxiliary capacitance line C1, the source line S1, thesource line S2, the pixel electrode PE, the gate shield electrode GS, afirst insulating film 11, a second insulating film 12, a thirdinsulating film 13, and the first alignment film AL1, etc., in the innerside of the first insulating substrate 10, i.e., on a surface facing thecounter substrate CT.

The gate line G1, the gate line G2, and the auxiliary capacitance lineC1 are formed on the first insulating film 11, and covered with thesecond insulating film 12. The source line S1 and the source line S2 areformed on the second insulating film 12, and covered with the thirdinsulating film 13. That is, the second insulating film 12 correspondsto an interlayer insulating film between the gate lines G1, G2 and thesource lines S1, S2.

The main pixel electrode PA of the pixel electrode PE, the gate shieldelectrode GS1, the gate shield electrode GS2, etc., are formed on theupper surface of the same insulating film, i.e., the upper surface ofthe third insulation film 13. The pixel electrode PE and the gate shieldelectrode GS can be formed by the same material.

The main pixel electrode PA is located in the inner side of the pixel PXrather than the position on the adjoining gate line G1 and the gate lineG2. The gate shield electrode GS1 is located on the gate line G1. Thegate shield electrode GS2 is located on the gate line G2. In addition,on the source line S1 and the source line S2, it is not necessary toarrange the electrodes (shield electrode, etc.) which have a functionequivalent to the common electrode CE. This is because even if electricfield leaks arise between the source line S and the pixel electrode PE,the leaked electric field is formed substantially in parallel with thefirst direction X which is the initial alignment direction of the liquidcrystal molecule LM, therefore the leaked electric field does not give abad influence on the display.

The first alignment film AL1 is arranged on the array substrate ARfacing the counter substrate CT, and extends to whole active area ACT.The first alignment film AL1 covers the pixel electrode PE, etc., and isarranged also on the third interlayer insulating film 13. The firstalignment film AL1 is formed of the material which shows a horizontalalignment characteristics.

The counter substrate CT is formed using a second insulating substrate20 which has a transmissive characteristics. The counter substrate CTincludes a black matrix BM, a color filter CF, an overcoat layer OC, acommon electrode CE, and a second alignment film AL2, etc., in theinternal surface of the second insulating substrate 20 facing the arraysubstrate AR.

The black matrix BM is formed on the second insulating substrate 20defining each pixel PX, and forms an aperture portion AP. That is, theblack matrix BM is arranged so that line portions, i.e., the sourceline, the gate line, the auxiliary capacitance line, the switchingelement SW, may counter the black matrix BM. Herein, the black matrix BMincludes a portion located above the source lines S1 and S2 extendingalong the second direction Y, and a portion located above the gate linesG1 and G2 extending along the first direction X, and is formed in theshape of a lattice. The black matrix BM is formed in an internal surface20A of the second insulating substrate 20 facing the array substrate AR.

The color filter CF is arranged corresponding to each pixel PX. That is,while the color filter CF is arranged in the aperture portion AP in theinternal surface 20A of the second insulating substrate 20, a portionthereof runs on the black matrix BM. The colors of the color filters CFarranged in adjoining pixels PX in the first direction X differmutually. For example, the color filters CF are formed of resinmaterials colored by three primary colors of red, blue, and green,respectively. The red color filter CFR formed of resin material coloredin red is arranged corresponding to the red pixel. The blue color filterCFB formed of resin material colored in blue is arranged correspondingto the blue pixel. The green color filter CFG formed of resin materialcolored in green is arranged corresponding to the green pixel. Theboundary between the adjoining color filters CF is located in a positionwhich overlaps with the black matrix BM.

The overcoat layer OC covers the color filter CF. The overcoat layer OCeases influence of concave-convex of the surface of the color filter CF.

The main common electrode CA1 and main common electrode CA2 of thecommon electrode CE, etc., are formed on the overcoat layer OC facingthe array substrate AR, and located under the black matrix BM. The maincommon electrode CA1 is located above the gate shield electrode GS1.Moreover, the gate line G1 is located under the main common electrodeCA1. The main common electrode CA2 is located above the gate shieldelectrode GS2. Moreover, the gate line G2 is located under the maincommon electrode CA2.

In the above-mentioned aperture portion AP, the region between the pixelelectrode PE and the common electrodes CE, that is, between the pixelelectrode PE and the main common electrodes CA1, and between the mainpixel electrode PA and the main common electrodes CA2 corresponds to atransmissive regions in which the backlight can penetrate.

The second alignment film AL2 is arranged on the counter substrate CTfacing the array substrate AR, and extends to whole active area ACT. Thesecond alignment film AL2 covers the common electrode CE and theovercoat layer OC, etc. The second alignment film AL2 is formed of thematerials having horizontal alignment characteristics.

The array substrate AR and the counter substrate CT as mentioned-aboveare arranged so that the first alignment film AL1 and the secondalignment film AL2 face each other. In this case, a pillar-shaped spaceris formed integrally with one of the substrates by resin materialbetween the first alignment film AL1 on the array substrate AR and thesecond alignment film AL2 on the counter substrate CT. Thereby, apredetermined gap, for example, a 2-7 μm cell gap, is formed. The arraysubstrate AR and the counter substrate CT are pasted together by sealmaterial which is not illustrated, in which the predetermined cell gapis formed, for example.

The liquid crystal layer LQ is held at the cell gap formed between thearray substrate AR and the counter substrate CT, and is arranged betweenthe first alignment film AL1 and the second alignment film AL2. Theliquid crystal layer LQ contains liquid crystal molecules which are notillustrated. The liquid crystal layer LQ is constituted, for example, bypositive type liquid crystal material.

Moreover, the distance between the main pixel electrode PA and the gateshield electrode GS in the second direction Y is larger than thethickness of the liquid crystal layer LQ, e. g., more than twice thethickness of the liquid crystal layer LQ.

A first optical element OD1 is attached on an external surface 10B ofthe array substrate AR, i.e., the external surface of the firstinsulating substrate 10 which constitutes the array substrate AR, byadhesives, etc. The first optical element OD1 is located on a side whichcounters with the backlight unit 4 of the liquid crystal display panelLPN, and controls the polarization state of the incident light whichenters into the liquid crystal display panel LPN from the backlight unit4. The first optical element OD1 includes a first polarizing plate PL1having a first polarization axis (or first absorption axis) AX1. Otheroptical elements such as a retardation film may be arranged between thefirst polarizing plate PL1 and the first insulating substrate 10.

A second optical element OD2 is attached on an external surface 20B ofthe counter substrate CT, i.e., the external surface of the secondinsulating substrate 20 which constitutes the counter substrate CT, byadhesives, etc. The second optical element OD2 is located in a displaysurface side of the liquid crystal display panel LPN, and controls thepolarization state of emitted light from the liquid crystal displaypanel LPN. The second optical element OD2 includes a second polarizingplate PL2 having a second polarization axis (or second absorption axis)AX2. Other optical elements such as a retardation film may be arrangedbetween the second polarizing plate PL2 and the second insulatingsubstrate 20.

The first polarization axis AX1 of the first polarizing plate PL1 andthe second polarization axis AX2 of the second polarizing plate PL2 arearranged in the Cross Nicol state in which they substantially intersectsperpendicularly. At this time, one polarizing plate is arranged, forexample, so that its polarization axis is arranged substantially inparallel with or in orthogonal with the extending direction of the pixelelectrode PA or the main common electrode CA. That is, when theextending directions of the main pixel electrode PA and the main commonelectrode CA are the first direction X, the absorption axes of onepolarizing plate is substantially in parallel with the first direction X(crossing orthogonally with the second direction Y), or crossesorthogonally with the first direction X (in parallel with the seconddirection Y).

One polarizing plate is arranged, for example, so that the polarizationaxis is arranged in the initial alignment direction of the liquidcrystal molecule, i.e., in orthogonal with or in parallel with the firstalignment treatment direction PD1 or the second alignment treatmentdirection PD2. When the initial alignment direction is in parallel withthe first direction X, the polarization axis of one polarizing plate isin parallel with the first direction X or the second direction Y.

In one example shown in FIG. 3B, the first polarizing plate PL1 isarranged so that the first polarization axis AX1 is in parallel with theextending direction of the main pixel electrode PA, i.e., the initialalignment direction (the first direction X) of the liquid crystalmolecule LM. The first polarization axis AX1 is arranged in parallelwith the first direction X. The second polarizing plate PL2 is arrangedso that the second polarization axis AX2 orthogonally intersects withthe extending direction of the main pixel electrode PA, i.e., theinitial alignment direction of the liquid crystal molecule LM. Thesecond polarization axis AX2 is arrange in parallel with the seconddirection Y.

In other example shown in FIG. 3C, the second polarizing plate PL2 isarranged so that the second polarization axis AX2 is arranged inparallel with the extending direction of the main pixel electrode PA,i.e., the initial alignment direction of the liquid crystal molecule LM.The second polarization axis AX2 is arranged in parallel with the firstdirection X. The first polarizing plate PL1 is arranged so that thefirst polarization axis AX1 orthogonally crosses with the extendingdirection of the main pixel electrode PA, i.e., the initial alignmentdirection of the liquid crystal molecule LM. The first polarization axisAX1 is arrange in parallel with the second direction Y.

Next, an operation of the liquid crystal display panel LPN of theabove-mentioned structure is explained.

At the time of non-electric field state (OFF), i.e., when a potentialdifference (i.e., electric field) is not formed between the pixelelectrode PE and the common electrode CE, the liquid crystal moleculesLM of the liquid crystal layer LQ are aligned so that their long axisare aligned in the first alignment treatment direction PD1 of the firstalignment film AL1 and the second alignment treatment direction PD2 ofthe second alignment film AL2. In this state, the time of OFFcorresponds to the initial alignment state, and the alignment directionof the liquid crystal molecule LM corresponds to the initial alignmentdirection.

In addition, precisely, the liquid crystal molecules LM are notexclusively aligned in parallel with the X-Y plane, but are pre-tiltedin many cases. For this reason, the precise direction of the initialalignment is a direction in which an orthogonal projection of thealignment direction of the liquid crystal molecule LM is carried out tothe X-Y plane at the time of OFF.

Here, both of the first alignment treatment direction PD1 of the firstalignment film AL1 and the second alignment treatment direction PD2 ofthe second alignment film AL2 are directions in parallel to the seconddirection Y and the same directions each other. At the time of OFF, thelong axis of the liquid crystal molecule LM is initially alignedsubstantially in parallel to the first direction X. That is, the initialalignment direction of the liquid crystal molecule LM is in parallel tothe first direction X, i.e., makes an angle of 0° with respect to thefirst direction X, in which the main pixel electrode PA and the maincommon electrode CA extend.

FIG. 6 is a figure schematically showing the alignment state of theliquid crystal molecule LM in the liquid crystal layer LQ at the time ofOFF. In addition, although the liquid crystal molecule LM is generallyin the shape of a rod or a rugby ball, herein, the liquid crystalmolecule LM is illustrated by the shape of a cone. Each liquid crystalmolecule LM has a conic bottom in one end portion, and a conical vertexin the other end portion. Moreover, the cross-sectional view taken alongline A-B in the liquid crystal display panel LPN shown in FIG. 3A showsmain elements among the structures shown in FIG. 4, that is, the mainpixel electrode PA, the gate shield electrode GS1 and the gate shieldelectrode GS2 on the third insulating film 13 in the array substrate AR,and the main common electrode CA1 and the main common electrode CA2 onthe overcoat layer OC on the counter substrate CT. Moreover, thecross-sectional view taken along line C-D in the liquid crystal displaypanel LPN shown in FIG. 3A shows main elements among the structuresshown in FIG. 5.

In the cross-section of the liquid crystal layer LQ, the liquid crystalmolecule LM, is aligned substantially in horizontal (pre-tilt angle issubstantially zero) near the intermediate portion of the liquid crystallayer LQ. The liquid crystal molecule LM is aligned with a pre-tiltangle in which the alignment becomes symmetric with respect to theintermediate portion of the liquid crystal layer LQ in a portion nearthe array substrate AR (near the first alignment film AL1) and a portionnear the counter substrate CT (near the second alignment film AL2). Thatis, the liquid crystal molecule LM is aligned in a splay alignmentstate.

In the cross-sectional view taken along line A-B, seen from the sourceline S1 side, i.e., on the ending side of the alignment treatmentdirection, the liquid crystal molecule LMM of the intermediate portionof the liquid crystal layer LQ is aligned so that the liquid crystalmolecule LMM turns to the first direction X that is a normal directionof the figure, and the conic bottom turns to the front side. The liquidcrystal molecule LMB of the liquid crystal layer LQ near the arraysubstrate AR is aligned so that the conic bottom turns to the countersubstrate CT side on the near side of the first direction X, and theconic vertex turns to the array substrate AR side on the far side of thefirst direction X. The liquid crystal molecule LMU of the liquid crystallayer LQ near the counter substrate CT is aligned so that the conicbottom turns to the array substrate AR side on the near side of thefirst direction X, and the conic vertex turns to the counter substrateCT side on the far side of the first direction X.

In the cross-sectional view taken along line C-D, which looks the regionbetween the pixel electrode PA and the common electrode CA2 from thegate line G2 side, the liquid crystal molecule LMM of the intermediateportion of the liquid crystal layer LQ is aligned so that the conicbottom turns to the ending side of the alignment treatment direction(source line S1 side), and the conic vertex turns to the starting sideof the alignment treatment direction (source line S2 side) substantiallyin parallel with the X-Y plane. The liquid crystal molecule LMB of theliquid crystal layer LQ near the array substrate AR is aligned so thatthe liquid crystal molecule LMB rises to the counter substrate CT sideon the ending side of the first alignment treatment direction PD1, theconic vertex located on the starting side of the first alignmenttreatment direction PD1 turns to the array substrate AR side, and theconic bottom located on the ending side of the first alignment treatmentdirection PD1 turns to the counter substrate CT side. The liquid crystalmolecule LMU of the liquid crystal layer LQ near the counter substrateCT is aligned so that the liquid crystal molecule LMU rises to the arraysubstrate AR side on the ending side of the second alignment treatmentdirection PD2, the conic vertex located on the starting side of thesecond alignment treatment direction PD2 turns to the counter substrateCT side, and the conic bottom located on the ending side of the secondalignment treatment direction PD2 turns to the array substrate AR side.

At the time of OFF, a portion of the backlight from the backlight 4penetrates the first polarizing plate PL1, and enters into the liquidcrystal display panel LPN. The light which entered into the liquidcrystal display panel LPN is linearly polarized light which intersectsperpendicularly with the first absorption axis AX1 of the firstpolarizing plate PL1. The polarization state of the linearly polarizedlight changes with the alignment state of the liquid crystal molecule LMwhen the linearly polarized light passes the liquid crystal layer LQ.However, at the time of OFF, the polarization state of the linearlypolarized light which passes the liquid crystal layer LQ hardly changes.For this reason, the linearly polarized light which penetrates theliquid crystal display panel LPN is absorbed by the second polarizingplate PL2 which is arranged in Cross Nicol positional relationship withthe first polarizing plate PL1 (black display).

The liquid crystal molecule LM near the first alignment film AL1 isinitially aligned to the first alignment treatment direction PD1 byprocessing the first alignment film AL1 in the first alignment treatmentdirection PD1. Similarly, the liquid crystal molecule LM near the secondalignment film AL2 is initially aligned to the second alignmenttreatment direction PD2 by processing the second alignment film AL2 inthe second alignment treatment direction PD2. Further, in case the firstalignment treatment direction PD1 is in parallel with and the samedirection as the second alignment treatment direction PD2, the alignmentstate of the liquid crystal molecule LM of the liquid crystal layer LQbecomes the splay alignment state as mentioned above. The liquid crystalmolecule LMB near the first alignment film AL1 and the liquid crystalmolecule LMU near the second alignment film AL2 become symmetric withrespect to the intermediate portion of the liquid crystal layer LQ onthe upper and lower sides. For this reason, the visual angle incliningfrom the third direction Z, that is, the normal line direction of thesubstrate, is optically compensated by the liquid crystal molecule LMBand the liquid crystal molecule LMU. Therefore, when the first alignmenttreatment direction PD1 is in parallel with and the same as the secondalignment treatment direction PD2, in a black display, there are fewoptical leaks. Thereby, a high contrast ratio can be realized, and itbecomes possible to improve display grace.

On the other hand, in case potential difference (or electric field) isformed between the pixel electrode PE and the common electrode CE, i.e.,at the time of ON, the lateral electric field (or oblique electricfield) is formed in parallel with the substrates between the pixelelectrode PE and the common electrode CE. The liquid crystal molecule LMis affected by the electric field between the pixel electrode PE and thecommon electrode CE, and the alignment state changes. More practically,while the liquid crystal molecule LM maintains the splay alignment statein the cross section of the liquid crystal molecule LQ, the liquidcrystal molecule LM rotates in an acute angle direction with respect tothe initial alignment direction in the X-Y plane.

In the example shown in FIG. 3A, the liquid crystal molecule LQ alignssymmetric with respect to the main pixel electrode PA on the both sidessandwiching the main pixel electrode PA in one pixel PX. In the regionin the upper half of the pixel PX, i.e., the transmissive region betweenthe main pixel electrode PA and the main common electrode CA1, thealignment state of the liquid crystal molecule LM mainly changes by theelectric field between the main pixel electrode PA and the main commonelectrode CA1. In the X-Y plane, the liquid crystal molecule LM rotatesclockwise to the first direction X, and aligns so that it may turn tothe upper left in the figure. In the region in the lower half of thepixel PX, i.e., the transmissive region between the main pixel electrodePA and the main common electrode CA2, the alignment state of the liquidcrystal molecule LM mainly changes by the electric field between themain pixel electrode PA and the main common electrode CA2. In the X-Yplane, the liquid crystal molecule LM rotates counterclockwise to thefirst direction X, and aligns so that it may turn to the lower left inthe figure.

Thus, in each pixel PX, in case electric field is formed between thepixel electrode PE and the common electrode CE, the alignment directionof the liquid crystal molecule LM is divided into two or more directionsby the position which overlaps with the pixel electrode PE, and domainsare formed in each alignment direction. That is, two or more domains areformed in one pixel PX.

At the time of ON, a portion of the backlight which entered into theliquid crystal display panel LPN from the backlight 4 penetrates thefirst polarizing plate PL1, and enters into the liquid crystal displaypanel LPN. The light which entered into the liquid crystal display panelLPN is linearly polarized light which intersects perpendicularly withthe first absorption-axis AX1 of the first polarizing plate PL1. Whenthe linearly polarized light passes the liquid crystal layer LQ, thepolarization state of the linearly polarized light changes in accordancewith the alignment state of the liquid crystal molecule LM. For example,if the linearly polarized light in parallel to the first direction Xenters into the liquid crystal display panel LPN in the X-Y plane, whenpassing the liquid crystal layer LQ, the light receives influence ofphase difference by λ/2 by the liquid crystal molecule LM which isaligned in a 45°-225° direction or a 135°-315° direction with respect tothe first direction X (herein, λ is a wavelength of the light whichpenetrates the liquid crystal layer LQ). Thereby, the polarization stateof the light which passes the liquid crystal layer LQ becomes linearlypolarized light in parallel to the second direction Y. For this reason,at the time of ON, at least a portion of the light which passes theliquid crystal layer LQ penetrates the second polarizing plate PL2(white display). However, in the position which overlaps with the pixelelectrode or the common electrode, since the liquid crystal moleculemaintains the initial alignment state, it becomes a black display likethe time of OFF.

As mentioned above, in the structure according to this embodiment, thealignment direction of the liquid crystal molecule LM in one pixel isdivided at least into two directions in the X-Y plane at the time of ON.The three-dimensional alignment state of the liquid crystal molecule LMin the liquid crystal layer LQ is mentioned later.

In order to realize the alignment state, it is necessary to provide themain common electrode CA1 and the main common electrode CA2 as thecommon electrode CE in addition to the pixel electrode PE having themain pixel electrode PA. That is, the gate shield electrode CS arrangedon the array substrate AR is provided to shield electric field fromother lines, to reinforce electric field required for the alignmentcontrol of the liquid crystal molecule LM, to form electric fieldrequired for the alignment control of the liquid crystal molecule LM inthe adjoining pixels, or to make redundancy of the common electrode CE.Therefore, they are not indispensable to form the multi domains.

FIG. 7 is a figure schematically showing the alignment state of theliquid crystal molecule LM in the liquid crystal layer LQ at the time ofON. Also in the FIG. 7, the liquid crystal molecule LM is illustrated bythe shape of a cone like FIG. 6. Moreover, only the principal portionsare illustrated about the cross-sectional view taken along lines A-B andC-D.

In the cross-sectional view of the liquid crystal layer LQ, thealignment of the liquid crystal molecule LM still maintains the splayalignment state like the time of OFF.

In a cross-sectional view taken along line A-B, the liquid crystalmolecule LM between the main pixel electrode PA and the main commonelectrode CA1 aligns so that the liquid crystal molecule LM turns fromthe main pixel electrode PA to the main common electrode CA1. The liquidcrystal molecule LMM1 of the intermediate portion, the liquid crystalmolecule LMB1 near the array substrate AR, the liquid crystal moleculeLMU1 near the counter substrate CT of the liquid crystal layer LQ alignsso that the respective conic bottoms turn to the main common electrodeCA1 side on the near side of the first direction X, that is, the normalline of the figure, and the conic vertex turns to the main pixelelectrode PA on the far side of the first direction X. The liquidcrystal molecule LMM1 of the liquid crystal layer LQ aligns in parallelwith array substrate AR and the counter substrate CT. The liquid crystalmolecule LMB1 of the liquid crystal layer LQ aligns so that the conicbottom rises to the counter substrate CT, i.e., the conic bottom turnsto the main common electrode CA1. The liquid crystal molecule LMU1 ofthe liquid crystal layer LQ aligns so that the conic bottom rises to thearray substrate AR, i.e., the conic bottom turns to the shield electrodeGS1. The alignment states of the liquid crystal molecules LMM1, theliquid crystal molecule LMB1, and the liquid crystal molecule LMU1maintain the splay alignment state.

In the cross-sectional view taken along line A-B, the liquid crystalmolecule LM between the main pixel electrode PA and the main commonelectrode CA2 aligns so that the liquid crystal molecule LM turns fromthe main pixel electrode PA to the main common electrode CA2. The liquidcrystal molecule LMM2 of the intermediate portion, the liquid crystalmolecule LMB2 near the array substrate AR, and the liquid crystalmolecule LMU2 near the counter substrate CT of the liquid crystal layerLQ align so that the respective conic bottoms turn to the first maincommon electrode CA2 side on the near side of the first direction X, andthe conic vertex turns to the main pixel electrode PA on the far side ofthe first direction X. The liquid crystal molecule LMM2 of the liquidcrystal layer LQ aligns in parallel with the array substrate AR and thecounter substrate CT. The liquid crystal molecule LMB2 of the liquidcrystal layer LQ aligns so that the conic bottom rises to the countersubstrate CT, i.e., the conic bottom turns to the main common electrodeCA2. The liquid crystal molecule LMU2 of the liquid crystal layer LQaligns so that the conic bottom rises to the array substrate AR, i.e.,the conic bottom turns to the shield electrode GS2. The alignment statesof the liquid crystal molecules LMM2, the liquid crystal molecule LMB2,and the liquid crystal molecule LMU2 maintain the splay alignment state.

In the cross-sectional view taken along line C-D, which looks at theregion between the main pixel electrode PA and the main common electrodeCA2 from the gate line G2, the liquid crystal molecule LMM2 of theintermediate portion, the liquid crystal molecule LMB2 near the arraysubstrate AR, and the liquid crystal molecule LMU2 near the countersubstrate CT align so that the respective conic bottoms on the endingside of the alignment treatment direction are located on the near sideof the second direction Y, that is the normal line of the figure, andthe conic vertex on the starting side of the alignment treatmentdirection is located on the far side of the second direction Y. Theliquid crystal molecule LMM2 aligns in parallel with the X-Y plane. Theliquid crystal molecule LMB2 aligns so that the conic bottom located onthe ending side of the first alignment treatment direction PD1 turns tothe counter substrate CT side and is located on the near side of thesecond direction Y. The conic vertex located on the starting side of thefirst alignment treatment direction PD1 turns to the array substrate ARside and is located on the far side of the second direction Y. Theliquid crystal molecule LMU2 near the counter substrate CT is aligned sothat the conic bottom located on the ending side of the second alignmenttreatment direction PD2 turns to the array substrate AR side and islocated on the near side of the second direction Y. The conic vertexlocated on the starting side of the second alignment treatment directionPD2 turns to the counter substrate CT side and is located on the farside of the second direction Y.

Thus, the liquid crystal molecule LMU1, the liquid crystal moleculeLMB1, the liquid crystal molecule LMU2, and the liquid crystal moleculeLMB2 align in different directions, respectively, in thethree-dimensional space of the liquid crystal layer LQ, at the time ofON. Therefore, it becomes possible to form substantially four domains inone pixel by the respective liquid crystal molecules. Even at the timeON, in the visual angle direction inclined from the third direction Z,the display is compensated by the combination of the liquid crystalmolecule LMU1 and the liquid crystal molecule LMB1, and the combinationof the liquid crystal molecule LMU2 and the liquid crystal moleculeLMB2. Therefore, the visual angle capable obtaining high transmissivitycan be expanded without generating of gradation inversion, and wideviewing angle is attained.

Moreover, since high transmissivity is obtained in the electrode gapbetween the pixel electrode PE and the common electrode CE according tothis embodiment, it becomes possible to correspond by expanding theinter-electrode distance between the pixel electrode PE and the maincommon electrode CA in order to make transmissivity of each pixel highenough.

Moreover, in the display device with high resolution, the second pitchbetween the source lines S in one pixel PX becomes narrow. If thedistance between the main pixel electrode PA and the main commonelectrode CA are arranged in parallel to the source lines S, there is apossibility that inter-electrode distance between the main pixelelectrode PA and the main common electrode CA cannot be fully taken. Onthe other hand, the first pitch is larger than the second pitch. If themain pixel electrode PA and the main common electrode CA are arranged inparallel with the gate line G, it becomes possible to take theinter-electrode distance between the main pixel electrode PA and themain common electrode CA sufficiently even in a high resolution displayspecification in which the second pitch is small.

Here, the relation between the first pitch and the second pitch of onepixel is described below. One unit (picture element) is constituted bythe minimum number of adjoining pixels among the pixels which correspondto R (red), G (green), B (blue) of the color filter, respectively. Thepixel pitch is designed so that the picture element may become anapproximately square. That is, if one picture element is formed of threepixels having color filters, respectively, extending in the firstdirection X, the first pitch between the gate lines is larger than thesecond pitch between the source lines in one pixel. That is, the firstpitch is larger substantially three times than the second pitch.Considering the relationship between the first pitch and the secondpitch, the main common electrode CA is arranged in parallel to the gateline so that the inter-electrode distance between the main commonelectrode CA1 and main common electrode CA2 may become substantiallyequal to the first pitch. Further, the main pixel electrode PA isarranged between the two main common electrodes CA (preferably, in thecenter between the two main common electrodes CA). Thereby, it becomespossible to secure the inter-electrode distance which can maintain hightransmissivity. That is, the transmissive region contributing thedisplay is formed using the distance of the long end of the pixel PX.Therefore, it becomes possible to secure sufficient distance between theelectrodes by arranging the main pixel electrode PA and the main commonelectrode CA in parallel to the short end of the pixel PX. Even in thedisplay device of high resolution in which the second pitch becomessmall, it becomes possible to make transmissivity high enough in onepixel. Further, it becomes possible to obtain a wide viewing angle bythe multi-domain structure.

In addition, although the color filters of three primary colors RGB arearranged in the first direction X according to this embodiment, theabove technique is applicable to the color filter of four-primarycolors, such as R (red), G (green), B (blue), and Y (yellow) or moreprimary colors. In the four primary colors (R, G, B, Y), that is, thetransmissive region contributing the display is formed using thedistance of the long end of the pixel PX like the case of thethree-primary colors (R, G, B). The same effect is obtained by arrangingthe main pixel electrode PA and the main common electrode CA in parallelto the short end of the pixel PX.

Moreover, in case the distance between the source lines is larger thanthat between the gate lines in the pixel, that is, in case the long endof the pixel PX is an end in parallel to the gate line G and the shortend of pixel PX is an end in parallel to the source line S, the mainpixel electrode PA and the main common electrode CA are arranged inparallel to the source line S so that the second pitch between thesource lines can be used. Practically, the main common electrodes CA arearranged in parallel to the source line so that the distance between thetwo main common electrodes CA may become equal to the second pitchbetween the source lines S. That is, the two main common electrodes CAare arranged so that they may locate above the source line S,respectively. It is preferable that the main pixel electrode PA isarranged substantially in the center portion of the pixel PX, that is,the main pixel electrode PA is arranged so that the distances betweenthe main pixel electrode PA and the each of the main common electrodesCA are substantially the same. Thereby, the same effect as the above isobtained.

In addition, the above arrangement of the main common electrode CA andthe main pixel electrode PA may be changed. That is, in one pixel PX,two main pixel electrodes PA are arranged near a pair of short ends ofthe pixel PX, respectively, and one main common electrode CA is arrangedbetween the two main pixel electrodes PA.

In the display devices in which the pixel pitch is different,respectively, a peak condition of a transmissivity distribution can beused by changing the electrode gap between the pixel electrode PE andthe common electrode CE according to this embodiment. That is, in thedisplay mode according to this embodiment, it becomes possible to offerthe display panel having various pixel pitches by setting upinter-electrode distance without necessarily using microscopicprocessing corresponding to the product specification from lowresolution with a comparatively large pixel pitch to high resolutionwith a comparatively small pixel pitch. Therefore, it becomes possibleto realize the demand for high transmissivity and high resolutioneasily.

According to this embodiment, the transmissivity falls sufficiently inthe region in which the liquid crystal molecules overlap with the blackmatrix layer This is because the leak of electric field does not occuroutside of the pixel from the common electrode CE, and undesired lateralelectric field is not produced between the adjoining pixels on the bothsides of the black matrix BM. That is, it is because the liquid crystalmolecule of the region which overlaps with the black matrix BM maintainsthe initial alignment state like at the time OFF (or the time of a blackdisplay). Furthermore, it is because that while the common electrode CEis not arranged on the source line S, the leaked light between thesource line S and the pixel electrode PE is formed in a direction inparallel with the first direction that is the initial alignmentdirection of the liquid crystal molecule LM, and the liquid crystalmolecule LM in the circumference maintains the initial alignment state.Accordingly, even in case the color of the color filter layers CF of theadjoining pixels is different, it becomes possible to suppress the mixedcolor, and also the reduction of the contrast rate.

Moreover, when an assembling shift occurs between the array substrate ARand the counter substrate CT, a difference may arises in distancesbetween the respective common electrodes CE of the both sides of thepixel and the pixel electrode PE. However, the alignment shift isproduced in common to all the pixels PX, there is no difference in theelectric field distribution between the pixels PX, and the influence tothe display of the image is negligible. Even if the assembling shiftarises between the array substrate AR and the counter substrate CT, itbecomes possible to control the undesirable electric field leak to theadjoining pixels. For this reason, even if it is in a case where thecolor of the color filter differs between the adjoining pixels, itbecomes possible to control the generation of the mixed colors, and alsobecomes possible to suppress the falls of color reproducibility natureand the contrast ratio.

According to this embodiment, the main common electrode CA counters withthe gate line G. When the main common electrode CA1 and the main commonelectrode CA2 are especially arranged on the gate line G1 and the gateline G2, respectively, the aperture portion AP which contributes to thedisplay can be expanded as compared with the case where the main commonelectrode CA1 and the main common electrode CA2 are arranged on thepixel electrode PA side rather than above the gate line G1 and the gateline G2, and it becomes possible to improve the transmissivity of thepixel PX.

Moreover, it becomes possible to expand the distances between the mainpixel electrode PE and the main common electrode CA1, and between themain pixel electrode PE and the main common electrode CA2 by arrangingeach of the main common electrodes CA1 and the main common electrode CA2above the gate line G1 and the gate line G2, respectively, and alsobecomes possible to form more horizontal electric field closer to thehorizontal direction. Further, it becomes possible to set the distancebetween the main pixel electrode PE and the common electrode CE largeenough against the variation of the distance between the electrodes dueto the assembling shift. Accordingly, the illumination variation can bereduced due to the assembling shift.

According to this embodiment, the array substrate AR includes the gateshield electrode GS located in the both sides sandwiching the pixelelectrode PE. Since the gate shield electrode GS counters with the gateline G, it becomes possible to shield undesirable electric field fromthe gate line G. For this reason, it can be controlled that undesirablebias is impressed from the gate line G to the liquid crystal layer LQ,and it also becomes possible to suppress the generating of defectdisplay such as the printing picture and the optical leak resulting fromthe alignment defect of the liquid crystal molecule.

Furthermore, at the time of ON, since horizontal electric field ishardly formed (or sufficient electric field to drive the liquid crystalmolecule LM is not formed) on the main pixel electrode PE or the commonelectrode CE, the liquid crystal molecule LM hardly moves from theinitial alignment direction like at the time of OFF. For this reason, asmentioned-above, even if the pixel electrode PE and the common electrodeCE are formed of the electric conductive material with the lighttransmissive characteristics in these domains, backlight hardlypenetrates, and hardly contributes to the display at the time of ON.Therefore, the pixel electrode PE and the common electrode CE do notnecessarily need to be formed of a transparent electric conductivematerial, and may be formed using non-transparent electric conductivematerials, such as aluminum (Al), titanium (Ti), silver (Ag), molybdenum(Mo), tungsten (W), and chromium (Cr).

When at least one of the pixel electrode PE and the common electrode CEis formed of the above-mentioned opaque electric conductive material,the linearly polarized light which entered into the liquid crystaldisplay panel LPN is in parallel with or intersects perpendicularly theextending direction of the edge of the pixel electrode PE or the commonelectrode CE. Moreover, the extending direction of the gate line G, theauxiliary capacitance line C, and the source line S, respectively,formed of the above opaque electric conductive materials issubstantially in parallel with or intersects perpendicularly thelinearly polarized light. For this reason, in the reflected light by theedge of the pixel electrode PE, the common electrode CE, the gate lineG, the auxiliary capacitance line C, and the source line S, thepolarized face is not disturbed easily, and the polarized face can bemaintained in the state where the linearly polarized light passed thefirst polarizing plate PL1. Therefore, since the linearly polarizedlight which penetrated the liquid crystal display panel LPN at the timeof OFF is fully absorbed by second polarizing plate PL2 which is apolarizer, it becomes possible to control optical leak. That is,transmissivity can be fully reduced in the case of a black display, andit becomes possible to control the fall of a contrast ratio. Moreover,it is not necessary to make the width of the black matrix BM large forthe measure against the optical leak in the circumference of the pixelelectrode PE or the common electrode CE. Accordingly, it becomespossible to control reduction of the area of the aperture portion AP anddecrease of the transmissivity at the time of ON

Moreover, although the case where the liquid crystal layer LQ isconstituted by the liquid crystal material having positive dielectricanisotropy (positive type) is explained, the liquid crystal layer LQ maybe constituted by liquid crystal material having negative dielectricanisotropy (negative type).

In addition, in this embodiment, the structure of the pixel PX is notlimited to the above-mentioned example. Hereinafter, variations of thepixel structure in this embodiment are explained briefly, referring toFIGS. 8A, 8B, 8C, FIGS. 9A, 9B, and FIGS. 10A, 10B, 10C, 10D. Inaddition, in each figure, the liquid crystal molecule LMB near the arraysubstrate AR is illustrated. While the conic bottom is located in theending side of the first alignment direction PD1 and rises in the normaldirection of the figure, the conic vertex is located in the startingside of the first alignment direction PD1. Moreover, in each figure,both the main pixel electrode PA and the main common electrode CA areillustrated by being simplified. The illustration of the source line,the gate line, the auxiliary capacitance line, the switching element,etc., is omitted. The domain enclosed with a dashed line in the figurecorresponds to the pixel PX.

FIG. 8A corresponds to the structure according to this embodiment shownreferring FIG. 2 to FIG. 7.

The structures shown in FIG. 8B and FIG. 8C are different from thatshown in FIG. 8A in that a sub-common electrode CB extending in thesecond direction Y is provided in addition to the main common electrodeCA. The sub-common electrode CB is located on the source line S which isnot illustrated, and arranged either on the array substrate AR or thecounter substrate CT.

In the structure shown in FIG. 8B, the sub-common electrode CB linearlyextends in the second direction Y and is arranged only on the same sideof the pixel adjoining in the second direction Y, that is, only theright side or only the left side of the pixel PX. In a pair of adjoiningpixels PX in the X direction, the sub-common electrode CB in one pixelis arranged on the right-hand side of the pixel, and the sub-common CBin the other end pixel is arranged on the left-hand side of the pixel.

Although the spray alignment is carried out in each pixel at the time ofON and OFF, the alignment state of the liquid crystal molecule LMB isdifferent in respective pixels PX in which the sub-common electrode CBis arranged only on the left-hand side, and pixel PX in which thesub-common electrode CB is arranged only on the right-hand side. Thatis, in the pixel in which the sub-common electrode CB is arranged onlyon the left-hand side, while the liquid crystal molecule LMB rotatesclockwise in the domain of the upper portion in the pixel PX, the liquidcrystal molecule LMB rotates counterclockwise in the domain of the lowerportion. In the pixel in which the sub-common electrode CB is arrangedonly on the right-hand side, while the liquid crystal molecule LMBrotates counterclockwise in the domain of the upper portion in the pixelPX, the conic bottom turns to the array substrate AR side, and a conicvertex turns to the counter substrate CT side. On the other hand, in thedomain of the lower portion in the pixel PX, while the liquid crystalmolecule LMB rotates clockwise, the conic bottom turns to the countersubstrate CT side, and a conic vertex turns to the array substrate ARside.

In the structure shown in FIG. 8C, the sub-common electrode CB isarranged only on the right-hand side of one of the pixels adjoining inthe second direction Y, and arranged only on the left-hand side in theother pixel. In a pair of adjoining pixels PX in the X direction, thesub-common electrode CB of one pixel is arranged on the right-hand sideof the pixel, and the sub-common electrode CB of the other pixel isarranged on the left-hand side of the pixel. Since the alignment stateof the liquid crystal molecule in the above structure is the same asthat shown in FIG. 8B, the explanation is omitted.

The structures shown in FIG. 9A and FIG. 9B are different from thatshown in FIG. 8A in that a sub-pixel electrode PB extending in thesecond direction Y is provided in addition to the main pixel electrodePA. The sub-pixel electrode PB is connected with one end of the mainpixel electrode PA, and forms the pixel electrode of a T shape with themain pixel electrode PA. In the illustrated example, the sub-pixelelectrode PB is connected with the right-hand end of the main pixelelectrode PA in all the pixels PX. That is, the pixel electrodes PE ofall the pixels PX turn to the same direction.

The structure shown in FIG. 9A includes only the common electrode CA asthe common electrode, and the structure shown in FIG. 9B includes thesub-common electrode CB in addition to the common electrode CA. Thesub-common electrode CB shown in FIG. 9B linearly extends in the seconddirection Y, and arranged on the both sides of each pixel. That is, thesub-common electrode CB is arranged between the sub-pixel electrode PBof one pixel and the main pixel electrode PA of the other pixel. Thealignment state of the liquid crystal molecule is the same as that ofthe structure shown in FIG. 8A.

The structures shown in FIGS. 10A, 10B, 10C and 10D adopt the T shapepixel electrode PE like the structure shown in FIG. 9A and FIG. 9B. Inthe example shown in the figure, the directions of the respectiveelectrodes PE of the adjoining pixels in the first direction X isdifferent each other.

In FIGS. 10A and 10B, the pixel electrode PE of each pixel PX whichadjoins in the second direction Y turns to the same directionaltogether. In the pixel electrode PE of each pixel PX which adjoins inthe first direction X, each sub-pixel electrode PB faces each other. Inthe pixel electrode PE of each pixel PX which adjoins in the seconddirection Y, each sub-pixel electrode PB is located on the same straightline along the second direction Y. In addition, in the example shown inFIG. 10A, the pixel has only the main common electrode CA as the commonelectrode. In the example shown in FIG. 10B, the pixel has thesub-common electrode CB as the common electrode in addition to the maincommon electrode CA. The sub-common electrode CB shown in FIG. 10Blinearly extends in the second direction Y, and is arranged at theopposite side in which the sub-pixel electrode PB of each pixel PX isarranged. For example, in the pixel PX on the left-hand side shown inFIG. 10B, while the sub-common electrode CB is connected with the mainpixel electrode PA on the right-hand side, the sub-common electrode CBis arranged on the left-hand side of the pixel. Similarly, in the pixelPX on the right-hand side shown in FIG. 10B, while the sub-pixelelectrode PB is connected with the main pixel electrode PA on theleft-hand side, the sub-common electrode CB is arranged on theright-hand side of the pixel PX.

In FIGS. 10C and 10D, the direction of the pixel electrode PE of eachpixel PX which adjoins in the second direction Y is different eachother. In the pixel electrode PE of each pixel PX which adjoins in thefirst direction X in the upper row, each main pixel electrode PA faceseach other. In the pixel electrode PE of each pixel PX which adjoins inthe first direction X in the lower row, each main pixel electrode PBfaces each other. In addition, in the structure shown in FIG. 10C, thepixel has only the main common electrode CA as a common electrode. Thepixel shown in FIG. 10D includes the sub-common electrode CB in additionto the main common electrode CA. The sub-common electrode CB shown inFIG. 10D is arranged at the opposite side to the side in which thesub-pixel electrode PB of each pixel PX is arranged. For example, in thepixel PX on the left-hand side in the upper row shown in FIG. 10D, whilethe sub-pixel electrode PB is connected with the main pixel electrode PAon the left-handside, the sub-common electrode CB is arranged on theright-hand side of the pixel PX. In the pixel PX on the right-hand sidein the upper row, while the sub-pixel electrode PB is connected with themain pixel electrode PA on the right-hand side, the sub-common electrodeCB is arranged on the left-hand side of the pixel PX. In the pixel PX onthe left-hand side in the lower row shown in FIG. 10D, while thesub-pixel electrode PB is connected with the main pixel electrode PA onthe right-hand side, the sub-common electrode CB is arranged on theleft-hand side of the pixel PX. In the pixel PX on the right-hand sidein the lower row, while the sub-pixel electrode PB is connected with themain pixel electrode PA on the left-hand side, the sub-common electrodeCB is arranged on the right-hand side of the pixel PX.

Each alignment state of the liquid crystal molecule in the abovevariations are substantially the same, and the above-mentioned effect isacquired.

In the above examples, a first electrode corresponds to the pixelelectrode PE (main pixel electrode PA), and a second electrodecorresponds to the common electrode CA. However, the first electrode maybe exchanged by the second electrode. In this case, the first electrodecorresponds to the common electrode CA, and the second electrodecorresponds to the pixel electrode PE (main pixel electrode CA).

As explained above, according to the embodiments, it becomes possible tooffer the liquid crystal display device which can control degradation ofdisplay grace.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A liquid crystal display device, comprising: afirst substrate including: a pixel electrode including a main pixelelectrode extending in a first direction arranged in a pixel in whichthe length along the first direction is shorter than that along a seconddirection orthogonally crossing the first direction, an electricconductive material under the main pixel electrode, and a firstalignment film covering the pixel electrode; a second substrateincluding a second alignment film; and a liquid crystal layer heldbetween the first substrate and the second substrate having liquidcrystal molecules, wherein the pixel is formed in a rectangular shapehaving a pair of short ends along the first direction and a pair of longends along the second direction, the main pixel electrode is arrangedsubstantially in a center portion of the pixel apart from the pair ofthe short ends with equal distance, the first substrate includes a gateline extending in the first direction, a source line extending in thesecond direction, and a switching element connected with the gate lineand the source line and arranged in a region that overlaps with thesource line and the electric conductive material, and the switchingelement includes a drain line, and the drain line includes a firstportion extending in the second direction and facing the source line anda second portion extending in the first direction from the first portionand facing the electric conductive material in the center portion of thepixel.
 2. The liquid crystal display device according to claim 1,wherein a length of the main pixel electrode along the second directionis shorter than a length of the electric conductive material along thesecond direction.
 3. The liquid crystal display device according toclaim 1, wherein an insulating film is interposed between the pixelelectrode and the electric conductive material, and a retentioncapacitance is formed between the pixel electrode and the electricconductive material.
 4. The liquid crystal display device according toclaim 1, comprising a picture element formed of a plurality of pixelsfor displaying different colors, wherein the length of the pictureelement along the first direction is substantially same as that of thesecond direction.
 5. The liquid crystal display device according toclaim 1, wherein the first substrate includes a sub-pixel electrodeconnected with one end of the main pixel electrode and extending in thesecond direction.
 6. The liquid crystal display device according toclaim 5, wherein the pixel electrode is formed in a T-shape.
 7. Theliquid crystal display device according to claim 1, wherein the electricconductive material is arranged for each of a plurality of pixelsarranged along the first direction.